Hidden Treasures: Mopar Marine Engine - Deep Six

When most of us think Mopar, we think Dodge, Plymouth, and Chrysler, and sometimes even Imperial or DeSoto, but forget about an important part of the Chrysler Corporation's business, the marine division. Chrysler Marine built some of the most reliable marine engines in the industry, ranging from small outboards to big-block and first-generation Hemi inboard and stern-drive engines, even providing counter-rotating units in dual-engine applications. And while you may not have noticed a Mopar powerplant in any of the boats you've ridden in, it's likely only because the engine ran so well it stayed enclosed under the engine cover, purring smoothly. In fact, Mopar marine engines were so durable they often outlasted the boats they were in, which is what led our friend and Mopar enthusiast Jim Wilson to find this example.

Like most of us who end up with a boat, Jim wasn't looking for one when he found this antique Commander Marine tri-hull model. Actually, Jim didn't find the boat so much as ended up with it at the end of its life. The boat belonged to a neighbor, and Jim, being a car guy, never paid much attention to it, other than seeing the family taking it out on weekends and vacations. When not in use the boat sat in a structure within sight of Jim's shop, but he never paid much attention to it. After seeing the boat used regularly for years, it became apparent several years ago that the neighbors weren't using the boat much anymore, and that they had purchased a newer one to take its place. Making conversation with his neighbor, Jim asked about the older boat and was told it would probably be sold for scrap since the transom was rotten and not worth repairing, which would be a shame since the engine ran so well. When asked what kind of engine, the owner said, "a Chrysler Slant-Six," and Jim was immediately interested, striking a deal for the vessel and moving it to his shop from the neighbor's yard.

Like most Chrysler marine engines, this one still runs fine and is connected to a Volvo Penta-style outdrive unit which is common for the era. The serial number of the engine begins in the number 225, so we can assume the Slant Six displaces that number of cubic inches, but since horsepower and date of manufacture aren't clearly visible on the engine tag, we can only guess at those. Based on the styling of the boat and its controls and instrumentation, our speculation is that it was built in the '70s, though a little internet research says the company called Commander Marine was only in business from 1987 to 2002 and was located in the same city of Lakeland, Florida, where Jim found the boat.

Since the hull of this vessel is rotten at the stern, this boat won't see the water again and will likely be parted out. Because Chrysler marine engines were specially assembled with the best parts and techniques, this is a great find for someone who needs a Slant Six. There are differences, however, between marine and automotive engines, as these engines typically had looser piston-to-cylinder clearance than their automotive counterparts, being cooled with a constant supply of fresh (or salt) water. Additionally, the exhaust and often intake manifold of a marine engine are completely different, with water being routed through the exhaust.

While it's too bad this boat couldn't be made seaworthy again, we admire Jim's awareness, finding a Mopar engine in a place most of us wouldn't think to look. Best of all, Jim scored a good deal on a running engine, saving this Slant Six from being deep-sixed!